The invention relates to improvements in vibration damping apparatus, especially to improvements in apparatus which can be used between the engine and the power train of a motor vehicle. More particularly, the invention relates to improvements in vibration damping apparatus of the type wherein one or more dampers are disposed between two coaxial flywheels one of which can be driven by the crankshaft of the internal combustion engine and the other of which can drive the input shaft of a variable-speed transmission in a motor vehicle, preferably in response to engagement of a friction clutch.
It is already known to provide one flywheel of a pair of neighboring flywheels in a vibration damping apparatus with a chamber for one or more dampers which oppose angular movements of the flywheels relative to each other. Each damper can comprise a set of energy storing elements in the form of coil springs, and each set of coil springs can be installed in a discrete compartment of the chamber which is provided in one of the flywheels. For example, the chamber can contain a damper whose coil springs oppose rotation of one flywheel (which is driven by the crankshaft of the engine) relative to the other flywheel (which can rotate the input shaft of the variable-speed transmission). To this end, the other flywheel which can rotate the input shaft carries a flange having windows for portions of the coil springs and extending into the compartment of the chamber in the flywheel which is driven by the engine. The compartment for the coil springs can have a practically circular cross-sectional outline and can be at least partially filled with a viscous fluid, e.g., a fluid of greasy or paste-like consistency. The surfaces which bound the radially outermost portion of the compartment can closely follow the outlines of convolutions of the coil springs, and the radially innermost portion of the compartment can be sealed from the neighboring portions of the chamber save for a relatively narrow gap which permits the viscous fluid to flow from and into the compartment in response to rotation of one of the flywheels relative to the other flywheel. Reference may be had to the commonly owned copending patent application Ser. No. 063,301 filed June 17, 1987 by Oswald Friedmann.